I agree with the whatever is available at a reasonable price. My minimum is that it must be "approved for use in air cooled engines". No outboard oil for instance.

And unless you are running one of the sub 15cc baby gassers (which actually need 20:1). 32:1 mixture is plenty of oil in the bigger stuff.

The 20:1 mixture suggestions you see for these bigger engines is an old spec. It does work, but it leaves way more mess on the planes than necessary.